Okay, so we all know I hate certification. Art platforms should be as open as possible to allow small businesses, hobbyists, and even casual users to share their expressions and ideas. Certification is the basis for my distrust of Windows Store and the "modern" Windows platform altogether. When you have someone between you and sharing, terms will be dictated for every transfer.
I am reminded of Harvest Moon which was pressured with ESRB certification (unclear where the pressure was coming from, however) to remove same-gender relationships in a North American release. If you build censorship, they will come. This is not censorship… but keep that in mind.
That said, the PC Gaming Alliance (PCGA) should only get between you and an advertising logo. They will not prevent you from sharing your app, unlike Windows Store, but rather just not say you have a satisfactory title.
Testing will not be free, of course. A non-PCGA member will need to pay $500 per game to be submit their title for certification; another $2000 will be required to request help with certification from the organization.
Metrics that the certification looks at is whether it runs at a smooth 30FPS at 720p medium settings on some reference platform and whether it supports gamepad and couch use cases (if those users would reasonably expect that environment for the title… ex: StarCraft would probably be exempt).
I can see this being… okay. It is a bit pointless for users who do the slightest bit of research before they purchase a title. That said, under the condition that it will not be a mandatory certification, it might be beneficial for smaller companies to market their goods. Cheap endorsement for small businesses is not a bad thing as long as it does not lock the art, itself, in any way.